Using internal ribosome entry sites to facilitate engineering of insect cells and used in secretion proteins production

• A non-lytic plasmid based bi-cistronic baculovirus-free insect cell expression was developed.• PnV539 IRES but not RhPV IRES functioned well in Sf21 cells through the plasmid-based baculovirus-free insect cell expression system.• Combined the PnV539 IRES with enhanced green fluorescent protein (EGFP) along with blasticidin-resistant gene to facilitate the isolation of the stably transformed insect cells.